Edge Wall Research Articles

Control of Acoustic Tone Formation using Shape Geometry Modifications and Jet Blowing in a Cavity experiencing Supersonic Flow

Acoustics tones have caused significant damage to sensitive electronic equipment and aircraft respectively. The effects become severe in cavities experiencing turbulent flows and could lead to human fatalities. Studies have compared the effects of cover plate (CP) and jet-blowing (JB) systems in suppressing the propagation of these undesirable effects. The sound pressure levels (SPL) were observed to decrease by 10% and 3% in the former and latter respectively. This study critically examines the combined effect of CP geometry modifications, jet orifice positions as well as integration with other established flow control techniques (FCT) with the possibility of achieving further attenuation in the system. Geometric sizes of the CP are set to 20%, 25% and 30% of the cavity length, with a length-to-depth ratio (l/d) of 5.07 and simulated in a flow field with a Mach number of 1.5. Also, four orifices for jet blowing are varied on the cavity leading and trailing edge wall. The trailing edge modification and trailing edge curvature are also implemented on the cavity. The k-ꙍ turbulence model and second-order discretization method are used to perform the computation. Results show that the trailing edge region produced the largest pressure fluctuations. Also, it was observed that longer cover plates (0.3l) permit the formation of self-oscillating frequencies as the flow field is brought closer to the trailing edge. However, the further inclination of the trailing wall will ensure prompt evacuation and dissipation of the flow turbulence energy. At the trailing edge, the jet-blowing control technique successfully attenuated approximately 10dB in SPL, though a significant amount of turbulence was introduced into the system. Overall, the trailing edge modification, inclined cover plate with a 0.25l and jet blowing on the trailing and leading edges produced an approximate 27.5% reduction in acoustic tone suppression.

High precision aerodynamic heat prediction method based on data augmentation and transfer learning

Data-driven modeling methods have become one of the main technologies for predicting aerodynamic heat in hypersonic conditions. However, due to the limitations of wind tunnel experimental conditions, the spatial distribution of aerothermal wind tunnel experimental data is often sparse, and the sample size is relatively small. Furthermore, there is a lack of direct correlation in the aerodynamic heat distribution data among different shapes of vehicles, which poses challenges for constructing high-performance data-driven aerodynamic heat prediction models. To address these issues, this paper proposes a high-precision aerodynamic heat modeling and prediction method based on data augmentation and transfer learning. First, integrating the concept of data fusion, we propose to enhance the sparse aerothermal wind tunnel experimental data by using deep neural networks and introducing low-precision numerical computation results. Next, based on the close physical correlation between boundary layer outer edge information and wall surface aerodynamic heat, we construct the aerodynamic heat prediction model ED-ResNet using a double-series residual neural network. Finally, by fine-tuning the ED-ResNet model for transfer learning, high-precision predictions of aerothermal wind tunnel experimental results for different shaped vehicles are achieved under small sample conditions. Verification using hypersonic double-ellipsoid, blunt cone, and blunt bicone shows that after data augmentation, the prediction error of the aerodynamic heat prediction model is significantly reduced to 1/3 of that when data augmentation is not used. Moreover, through transfer learning, the model effectively leverages existing hypersonic double-ellipsoid aerothermal wind tunnel experimental data to achieve high-precision predictions of aerodynamic heat distribution for blunt cone and blunt double cone under different incoming flow conditions, with normalized root mean square error(NRMSE) maintained below 10 %.

Mechanical Property of Thermoplastic Polyurethane Vascular Stents Fabricated by Fused Filament Fabrication

Vascular stents have many applications in treating arterial stenosis and other vascular-related diseases. The ideal vascular stent for clinical application should have radial support and axial bending mechanical properties that meet the requirements of vascular deformation coordination. The materials used for vascular stents implanted in the human body should have corresponding biocompatibility to ensure that the stents do not cause coagulation, hemolysis, and other reactions in the blood. This study fabricated four types of vascular stents, including inner hexagon, arrowhead, quadrilateral, and outer hexagonal, using fused filament fabrication technology and thermoplastic polyurethane (TPU) as materials. By evaluating the effects of edge width and wall thickness on the radial support and axial bending performance, it was found that the inner hexagonal stent exhibited the best radial support and axial bending performance under the same conditions. The design and fabrication of vascular stents based on 3D printing technology have promising application prospects in personalized customized vascular repair therapy.

Automated quality control analysis for American College of Radiology (ACR) digital mammography (DM) phantom images.

To develop and validate an automated software analysis method for mammography image quality assessment of the American College of Radiology (ACR) digital mammography (DM) phantom images. Twenty-seven DICOM images were acquired using Fuji mammography systems. All images were evaluated by three expert medical physicists using the Royal Australian and New Zealand College of Radiologists (RANZCR) mammography quality control guideline. To enhance the robustness and sensitivity assessment of our algorithm, an additional set of 12 images from a Hologic mammography system was included to test various phantom positional adjustments. The software automatically chose multiple regions of interest (ROIs) for analysis. A template matching method was primarily used for image analysis, followed by an additional method that locates and scores each target object (speck groups, fibers, and masses). The software performance shows a good to excellent agreement with the average scoring of observers (intraclass correlation coefficient [ICC] of 0.75, 0.79, 0.82 for speck groups, fibers, and masses, respectively). No significant differences were found in the scoring of target objects between human observers and the software. Both methods achieved scores meeting the pass criteria for speck groups and masses. Expert observers allocated lower scores to fiber objects, with diameters less than 0.61mm, when compared to the software. The software was able to accurately score objects when the phantom position changed by up to 25mm laterally, up to 5 degrees rotation, and overhanging the chest wall edge by up to 15mm. Automated software analysis is a feasible method that may help improve the consistency and reproducibility of mammography image quality assessment with reduced reliance on human interaction and processing time.

Numerical investigation of particle behavior and erosion wear in a centrifugal pump using coarse-grained Discrete Element Method

Erosion wear presents a significant challenge in the operation of hydrodynamic systems, particularly in centrifugal pumps. To address this issue, this study employs the coarse-grained Discrete Element Method (CGDEM) coupled with Computational Fluid Dynamics (CFD) to predict erosion wear areas and elucidate particle behavior dynamics. The simulation considers spherical solid particles (brown corundum) with diameters ranging from 0.3 mm to 1 mm and volume fractions of 15% and 5%. The flow field is calculated using the Navier-Stokes equations and the shear-stress-transport (SST) k-ω model. Particle movement is tracked using Newton’s second law, considering drag and gravitational forces. Results indicate that the highest turbulent kinetic energy (TKE) occurs at a flow rate of Q = 15 m3/h. Moreover, the pressure reduces slightly when the flow rate increases, although flow velocity might increase with volumetric discharge. Additionally, increased particle diameter leads to greater erosion wear, particularly on blade leading edges, the volute tongue area, and the volute casing belly region. As particle mass concentration intensifies, wear rates on the volute wall and inner hub edge also increase. The study’s robustness is demonstrated through alignment between experimental and numerical data. This investigation offers valuable insights into erosion dynamics in centrifugal pumps, crucial for enhancing operational efficiency and mitigating erosion-induced challenges in these critical systems.

In plane mechanical properties of hexagonal V-chiral and Tri-chiral metamaterials

The reasonable design of man-made multifunctional metamaterials with advanced mechanical and physical properties that are not found in nature is both challenging and important. In this paper, novel chiral structures are designed by adding V- and Tri- chiral elements to the typical hexagonal honeycomb substrate, so as to realize the modulation of in plane mechanical properties. Finite element simulations show that the Poisson's ratio of the hexagonal V-chiral structure is negative when the strain is greater than 0.4, and that of the hexagonal Tri-chiral structure is always negative. Quasi-static compression tests show that the introduction of chiral properties results in a stronger load-bearing capacity, and the hexagonal Tri-chiral structure has a stronger energy absorption (EA) and specific energy absorption (SEA) capability. A parametric study is carried out by means of FEM, by adjusting the geometrical parameters of the proposed structures, the performance in terms of energy absorption and compressive stiffness can be improved. Subsequently, Bloch-Floquet theorem is employed for the dispersion relations of the chiral metamaterials and the results show that compared to conventional hexagonal honeycomb, chiral metamaterials are able to generate band gaps in a lower frequency range. Numerical simulation results show that the bandwidth of the proposed novel chiral metamaterials can be tuned through a reasonable selection of hexagonal edge length, wall thickness and radius. Experimental investigations are conducted to test the vibration transmission rate of Structure Ⅲ, and the results prove that the structure is capable of vibration suppression in the target frequency band range. Finally, by filling Structure Ⅲ with steel columns, the structure generates band gaps in the lower frequency range, hence the application of this chiral metamaterial is broadened.

A domain wall and chiral edge currents in holographic chiral phase transitions

We investigate spatially inhomogeneous solutions in a top-down holographic model: the D3/D7 model which provides a holographic description of the chiral phase transition for a finite external magnetic field, chemical potential, and temperature. We numerically find a domain wall (or kink) solution in the three dimensional space, which incorporates between the chiral symmetry broken phase at the spatial infinity, under the homogeneous sources. Along with the inhomogeneity of the chiral condensate, the charge density is also spatially modulated. The modulated charge density and finite magnetic field lead to the chiral edge current close to the domain wall. We explore the dependences of those profiles on the chemical potential and temperature near the first and second order phase transition points. Our results indicate that the inhomogeneous solutions we found are in good agreement with those obtained by the Ginzburg-Landau theory in the vicinity of the transition points.

Suppression effect of the leading-edge groove on deep cavity noise at low speeds: Groove length

Detached Eddy Simulations combined with Ffowcs Williams–Hawkings acoustic analogy of subsonic flows over a deep cavity preceded by deep grooves with different lengths were conducted to investigate the effects of groove length on the flow characteristics and the noise suppression in the vicinity of the deep cavity. The length-to-depth ratio of the deep cavity is 2/3, and the length-to-depth ratios of the grooves are 1/2. The distance between the grooves and the cavity remains constant at twice the groove length. The groove length ranges from 5 mm to 30 mm. The Reynolds number based on the cavity length is 8 × 10−5. The analysis results indicate that all grooves studied in this paper have some effect on the distribution of sound energy of near-field noise and near-/far-field noise amplitude, but have no effect on the characteristic frequencies of cavity noise and far-field noise directivity. When the groove length is 15 mm and 20 mm, the deep grooves are most effective in suppressing deep cavity noise. The time-averaged velocities in the incoming boundary layer, shear layer, and wake region decrease, and the height of the boundary layer downstream of the cavity increases, which reduces the intensity of the interaction between the flow structure and solid wall downstream of the cavity, resulting in a reduction in flow-acoustic feedback noise. Meanwhile, the suppression effect of the groove flow on the cavity flow effectively alters the flow characteristics of the entire cavity mouth, the rear edge wall, and part of the bottom surface region, reducing the energy at these locations. This is the primary reason for the reduction in broadband noise and acoustic resonance noise.

A prediction model for drilling temperature of CFRP/Ti stacks and green cooling strategy considering chip ejection process

Drilling temperature has always been a hot issue in the drilling process of CFRP/Ti stacks. Accurately predicting drilling temperature is necessary for reliable optimization of drilling parameters. However, since the drilling process involves two materials and may affect each other, the prediction of temperature during drilling is still a challenge. In this paper, a novel drilling temperature model is established to predict the temperature distribution in CFRP workpiece during the drilling process of CFRP/Ti stacks, considering the minor cutting edge and titanium alloy chip ejection process. Specifically, according to different drilling phases, in addition to considering the heat source of the cutting zone of different materials, the heat source generated by the interaction of minor cutting edge and rebound hole wall of CFRP and the heat source formed by the thermal-mechanical effect of Ti chip ejection process are also considered. The results show that the prediction errors of peak temperature in CFRP entrance and stack interface region during drilling are within 15.8 % and 10.9 %, respectively, which indicates the validity of the model. Finally, the green cooling strategy (High and low frequency compound vibration-assisted drilling) is adopted to significantly reduce the peak temperature in the drilling process by controlling the chip morphology and ejection process, which further proves that the thermo-mechanical action of Ti chips on CFRP cannot be ignored, and provides reference for temperature modeling and low-damage processing of CFRP/metal stacks.

Reducing vibration and noise in honeycomb structure applied to automobile integrated water tank

This work uses modal acoustic transfer vector (MATV) technology in conjunction with vibration response analysis to determine optimal target optimization parameters for automobile integrated water tanks. The effects of square and hexagonal reinforcement honeycomb structures on the vibration damping performance of water tanks are analyzed, using an untreated smooth plane as a reference object. The study investigates the effects of honeycomb height, honeycomb length, and honeycomb thickness on the tank’s vibration damping performance. The results indicate that a hexagonal structure is more effective than a square structure in improving structural stiffness and reducing structural vibration. The height of the honeycomb structure is particularly effective in suppressing normal vibration of the structural surface, especially when the height exceeds 8 mm. A response surface model is developed based on the edge length, wall thickness, and height of the honeycomb, following the Box-Behnken central combinatorial test design principle. Considering the effect of interference of additional parts, the noise reduction is found to be most effective with a honeycomb side length L = 12 mm, height H = 4.91 mm, and wall thickness T = 2.5 mm. These parameters can be a guide for creating a new honeycomb reinforcement structure to better achieve vibration and noise reduction in automobile water tanks.

Global N-body simulation of gap edge structures created by perturbations from a small satellite embedded in Saturn’s rings

Small satellites embedded in Saturn’s ring – Daphnis and Pan – open a clear gap. Observations by the Voyager and Cassini spacecrafts have revealed various striking features of the gap structure, such as the density waves, sharp edge, and vertical wall structure. In order to explain these features in a single simulation, we perform a high-resolution (N∼106−107) global full N-body simulation of gap formation by an embedded satellite considering gravitational interactions and inelastic collisions among all ring particles and the satellite, while these features have been mostly investigated separately with different theoretical approaches: the streamline models, 1D diffusion models, and local N-body simulation. As a first attempt of a series of papers, we here focus on the gap formation by separating satellite migration with fixing the satellite orbit in a Keplerian circular orbit. We reveal how the striking gap features – the density waves, sharp edge, and vertical wall structure – are simultaneously formed by an interplay of the satellite-ring and ring particle–particle interactions. In particular, we propose a new mechanism to quantitatively explain the creation of the vertical wall structure at the gap edge. Inelastic collisions between ring particles damp their eccentricity excited by the satellite’s perturbations to enhance the surface density at the gap edge, making its sharp edges more pronounced. We find the eccentricity damping process inevitably raises the vertical wall structures the most effectively in the second epicycle waves. Particle–particle collisions generally convert their lateral epicyclic motion into vertical motion. Because the excited epicyclic motion is the greatest near the ring edge and the epicycle motions are aligned in the first waves, the conversion is the most efficient in the gap edge of the second waves and the wall height is scaled by the satellite Hill radius, which are consistent with the observations.

High gain narrow wall standing wave slotted waveguide antenna with flanges

ABSTRACT In this study, narrow (edge) wall standing wave slotted waveguide antenna design is proposed. This antenna operates at 2.812 GHz in S frequency band. Also, the design equations and slot characterization method are given in this study. This antenna is designed with two flanges to shape the elevation pattern and to increase the antenna gain. This antenna provides low cross polarization without using any polarizer or any other structure. The designed antenna is suitable for high gain and high-power applications. The performance of the proposed design is examined with simulations and verified with measurements.

Dynamics and impurity spectral characteristics of coaxial gun discharge plasma

<sec>The coaxial gun discharge can produce plasma jet with high velocity, high density and high energy density, and has extensive applications, such as in plasma space propulsion, simulation of the interaction between edge local mode and wall materials in ITER, fuel injection in magnetic confinement fusion devices, and laboratory astrophysics. In the pre-filled discharge mode or snowplow mode, the plasma current sheet is formed near the insulating layer surface and moves toward the end of the coaxial gun under Lorentz force. Plasma velocity, density and purity characteristics are very important research contents for the actual applications of coaxial gun. Emission spectrometry as a non-interference method can be used to diagnose a variety of plasma physical properties.</sec><sec>In this experiment, the effects of different discharge currents and gas pressures on the plasma dynamics, electron density and impurity emission spectra of coaxial gun discharge plasma are studied through the measurement of plasma photocurrent, emission spectra and the shooting of discharge images. The experimental results show that the acceleration time of the plasma in the gun decreases with current increasing in a range of 30–70 kA when the gas pressure is 10 Pa, the spectral intensity of anode and cathode impurities in plasma increase with current amplitude increasing. When the discharge current is 40 kA and the gas pressure is in a range of 10–70 Pa, the acceleration time of plasma increases with gas pressure rising, and the spectral intensity of the cathode impurity in the plasma decreases with the pressure increasing, while the spectral intensity of the anode impurity increases gradually, but its growth rate decreases continuously. The analysis indicates that the presence of metallic impurities originating from the electrode material limits the jet velocity of the plasma and is the main cause of the deviation from theoretical value. The plasma pinch effect at the nozzle of coaxial gun and the acceleration time of high-density arc in the gun are important factors affecting anode ablation. The impurity of cathode material is produced by ion bombardment sputtering, which mainly depends on the energy carried by ions. Therefore, a reasonable choice for discharge parameters is the key factor to obtain optimal plasma characteristics during the discharge of the coaxial gun.</sec>

Bubble rising near a vertical wall: Experimental characterization of paths and velocity

Trajectories of a single bubble rising in the vicinity of a vertical solid wall are experimentally investigated. Distinct initial wall-bubble distances are considered for three different bubble rising regimes, i.e., rectilinear, planar zigzag, and spiral. The problem is defined by three control parameters, namely, the Galilei number, Ga, the Bond number, Bo, and the initial dimensionless distance between the bubble centroid and the wall, L. We focus on high-Bond numbers, varying L from 1 to 4, and compare the results with the corresponding unbounded case, L→∞. In all cases, the bubble deviates from the expected unbounded trajectory and migrates away from the wall as it rises due to the overpressure generated in the gap between the bubble and the wall. This repulsion is more evident as the initial wall-bubble distance decreases. Moreover, in the planar zigzagging regime, the wall is found to impose a preferential zigzagging plane perpendicular to it when L is small enough. Only slight wall effects are observed in the velocity or the oscillation amplitude and frequency. The wall migration effect is more evident for the planar zigzagging case and less relevant for the rectilinear one. Finally, the influence of the vertical position of the wall is also investigated. When the wall is not present upon release, the bubbles have the expected behavior for the unbounded case and experience the migration only instants before reaching the wall edge. This repulsion is, in general, more substantial than in the initially present wall case.

Effects of various aftwall edge ramp on open cavities in a confined supersonic flow

An experimental study on the supersonic flow of Mach number 1.81 Over the rectangular cavity of L/D = 3 with different aft wall angles such as Baseline case 90° and aft wall edge ramp of 30°. Measurements of acoustic oscillations were carried out on the wall and floor of the cavity using unsteady pressure transducers. Schlieren flow visualization indicates the presence of a shear layer and the other shock features that are associated with the cavity flow field. In order to obtain the experimental results, data analysis was performed in the unsteady data Using statistical analytical techniques i.e., Fast Fourier Transform, Short Time Fourier Transform, and Coherence. After careful examination of the power spectra of the cavities, it is concluded that as the aft wall angle decreases by introducing the aft wall ramp, the amplitude decreases. It is clearly observed that the complete escape of vortices in Low angled cavity. From the correlation plot, the existence of the acoustic wave inside the cavity for all the cases is deduced. The maximum OASPL and static pressure values are observed at the aft wall. These results, the strength of the self-sustained oscillations and acoustic disturbance and mode switching were observed in the higher angled cavity 90°. Also, the mode switching co-existence was reduced in the aft wall edge ramp angle of 30°.

Influence of sulfate reducing bacteria cultured from the paddy soil on the solubility and redox behavior of Cd in a polymetallic system

As a toxic heavy metal, cadmium (Cd) easily enters into rice while rice grains greatly contribute to the dietary Cd intake in the populations consuming rice as a staple food. The availability of Cd in paddy soil determines the accumulation of grain Cd. Soil drainage leads to the remobilization of Cd, increasing bioavailability of Cd. In contrast, soil flooding results in little contribution of soil Cd to grain Cd, which is generally attributed to sulfate reduction induced by sulfate-reducing bacteria (SRB) in paddy soils. However, effects of SRB cultured from the paddy soil on the solubility and redox behavior of Cd have been seldom investigated before. Here, we used SRB enrichment cultures to investigate the temporal dynamics of Cd2+. The results showed that SRB enrichment cultures efficiently reduced solution redox potential (Eh) to less than −100 mV and gradually increased pH to neutral, demonstrating their ability to create a good anaerobic environment. The solubility of Cd obviously decreased in the anaerobic phase and Cd2+ was transformed into poorly dissolved CdS near the SRB cell wall edge. The addition of Zn2+ and/or Fe2+ further improved the decrease in Cd solubility and facilitated the formation of polymetallic sulfides as a consequence of promoting the production of S0 and dissolved sulfides (S2−/HS−) and the transformation of S0 into S2−/HS−. Little of Cd was detected in the media upon reoxidation, which was probably due to the high pH and the interaction between CdS and ZnS/FeS. Conclusively, these results demonstrate the detailed dynamic processes that explain the essential role of SRB in regulating the redox dynamics of chalcophile heavy metals and their bioavailability in paddy soils.

Turbulent Flow and Heat Transfer Enhancement for Turbine Blade Trailing Edge Cooling With Gyroid-Type Triply Periodic Minimal Surfaces

Abstract The Gyroid is a type of triply periodic minimal surface (TPMS) that has interconnected, perfectly curved topologies and excellent thermomechanical properties. Due to its topological feature to enhance heat transfer and self-support structure, this study presents numerical investigations of the flow, heat transfer, and pressure loss in various Gyroid architectures in a wedge-shaped channel, representing a trailing edge cooling for gas turbine blades. The Gyroid structures are partly arranged near the outlet of the wedged channel or are fully filled within the wedged channel. The local and overall flow and heat transfer mechanisms with different Gyroid configurations are compared to the baseline pin fins within the Reynolds number range of 10,000–30,000. The results show that for the case with partly infilled Gyroid structures, the overall heat transfer enhancement is higher by 39–102%, and the related pressure loss is higher by 93–154% than the baseline pin fins. For the case with fully infilled Gyroid structures, the total heat transfer is superiorly higher by 157–188%, and the related pressure loss is higher by 248–555% than the baseline pin fins. For all the Gyroid configurations, obviously improved cooling uniformity is achieved on the whole trailing edge wall. The significant heat transfer enhancement in the trailing edge channel with Gyroid structures is mainly due to a much increased wetted area, the generated helical and impingement flow through the curved interconnected channels and improved flow distribution within the wedged channel.

Biocompatibility of conformal silicon carbide on carbon nanowall scaffolds

Silicon carbide (SiC) was coated onto carbon nanowall (CNW) scaffolds using chemical vapor deposition with a vinylsilane precursor at 700 °C to investigate the influence of the wall edge width, wall-to-wall distance, and surface morphology. The wall edge width ranged from 10 nm to those filling the wall-to-wall space without disrupting the CNW morphology. When SiC-coated CNWs (SiC/CNWs) were used as scaffolds for cell culture, cell viability increased until the edge area ratio reached 40%. In over 40% of edge area ratio, cell viability was saturate and comparable to flat surfaces such as SiC films on the Si substrate (SiC/Si) and control samples prepared using polystyrene. Calcification was suppressed in the CNWs, SiC/CNWs, and SiC/Si scaffolds compared to polystyrene. Our results suggest that SiC-coated CNW scaffolds could suppress calcification and promote cell proliferation.

Surveying the effects of concave obstacles with different edge walls on hollow glycerin droplet impacting using the volume of fluid approach

The numerical analysis of the impact of a hollow droplet on a solid concave obstacle at various heights of the edge wall and impact velocity is presented in this study. The Volume Of Fluid (VOF) approach was used to simulate hollow droplet impact using OpenFoam software. The Newtonian, incompressible, and laminar properties of the glycerin hollow droplet are assumed. Hollow droplet collision hydrodynamic behavior and jet characteristics were explored. The height of the counter jet rose as the impact velocity and height of the edge wall increased. Maximum height and length have happened to case 8 in t = 2 ms and case 3 in t = 1 ms, so the amount of it is 9.75 and 19.75 mm, minimum height and length in the last time computed is 1.4 and 2.73 mm for cases 1 and 7, respectively.

Cross-flow vortices and their secondary instabilities in hypersonic and high-enthalpy boundary layers

Compared to the streamwise instability, the cross-flow instability in high-enthalpy flows has received relatively less attention, but the latter is of vital importance in the flow transition for practical configurations. This work aims to investigate the cross-flow primary and secondary instabilities in hypersonic and high-enthalpy boundary layers, considering thermochemical non-equilibrium (TCNE) effects. The numerical tools adopted include a high-order shock-fitting solver, nonlinear parabolized stability equations and secondary instability theory (SIT). The flow over a swept parabola is calculated at a free-stream Mach number of 16. It is found that TCNE has a destabilizing effect on the cross-flow mode with a non-catalytic wall. Two important non-dimensional parameters are summarized to explain this effect. One is the ratio between the wall and boundary-layer edge temperatures, and the other is the cross-flow Mach number. Due to nonlinear effects, the stationary cross-flow vortices evolve and exhibit the classic rollover structures as in lower-speed flows. Two different disturbance energy norms are used in the energy budget analysis to classify the secondary cross-flow instability modes. The results from SIT highlight the importance of type-IV modes in TCNE flows at the downwash region of the vortex. The type-IV modes arise with the combined contribution from the wall-normal (on top and trough of the vortex) and spanwise (in the downwash region) production terms. The type-I mode is dominant in the calorically perfect gas case with an adiabatic wall, whereas the type-IV mode has the largest growth rate in the TCNE cases irrespective of wall temperature variation.